In-plane resistivity anisotropy of single crystal SmFeAsO

In the vicinity of the superconducting dome in the phase diagram of iron-pnictides there exist a magnetically ordered phase accompanied by a nematic phase and a structural transition. Since all three phases belong to the same point group symmetry, it is a priori difficult to establish which of these phases is dominant. The fluctuations associated with the energetically dominant transition have been proposed as the driving force behind electronic pairing in the superconducting state. Therefore the identification of this transition is essential for further understanding the physics behind superconductivity in iron-pnictides. This thesis explores the relation between nematic strength and the superconducting critical temperatures in the pnictides. The in-plane resistivity anisotropy of single crystal SmFeAsO (Tc =55 K in optimally F-doped SmFeAs[O,F]) was investigated using four different sample geometries structured by focused ion beam methods. The results are compared to other iron...Show moreIn the vicinity of the superconducting dome in the phase diagram of iron-pnictides there exist a magnetically ordered phase accompanied by a nematic phase and a structural transition. Since all three phases belong to the same point group symmetry, it is a priori difficult to establish which of these phases is dominant. The fluctuations associated with the energetically dominant transition have been proposed as the driving force behind electronic pairing in the superconducting state. Therefore the identification of this transition is essential for further understanding the physics behind superconductivity in iron-pnictides. This thesis explores the relation between nematic strength and the superconducting critical temperatures in the pnictides. The in-plane resistivity anisotropy of single crystal SmFeAsO (Tc =55 K in optimally F-doped SmFeAs[O,F]) was investigated using four different sample geometries structured by focused ion beam methods. The results are compared to other iron-pnictides and it was observed that the maximal resistivity anisotropy is similar as to that in other iron-pnictides. These initial results clearly lay the groundwork for future experimental studies, in particular probing the relation between the crystal lattice and the nematicity.Show less

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In-plane resistivity anisotropy of single crystal SmFeAsO